邻苯二甲酰亚胺
聚合物
材料科学
聚合物太阳能电池
接受者
电子迁移率
轨道能级差
带隙
高分子化学
光电子学
化学
有机化学
分子
物理
复合材料
凝聚态物理
作者
Jianwei Yu,Peng Chen,Chang Woo Koh,Hang Wang,Kun Yang,Xin Zhou,Bin Liu,Qiaogan Liao,Jianhua Chen,Huiliang Sun,Han Young Woo,Shiming Zhang,Xugang Guo
标识
DOI:10.1002/advs.201801743
摘要
Highly efficient nonfullerene polymer solar cells (PSCs) are developed based on two new phthalimide-based polymers phthalimide-difluorobenzothiadiazole (PhI-ffBT) and fluorinated phthalimide-ffBT (ffPhI-ffBT). Compared to all high-performance polymers reported, which are exclusively based on benzo[1,2-b:4,5-b']dithiophene (BDT), both PhI-ffBT and ffPhI-ffBT are BDT-free and feature a D-A1-D-A2 type backbone. Incorporating a second acceptor unit difluorobenzothiadiazole leads to polymers with low-lying highest occupied molecular orbital levels (≈-5.6 eV) and a complementary absorption with the narrow bandgap nonfullerene acceptor IT-4F. Moreover, these BDT-free polymers show substantially higher hole mobilities than BDT-based polymers, which are beneficial to charge transport and extraction in solar cells. The PSCs containing difluorinated phthalimide-based polymer ffPhI-ffBT achieve a substantial PCE of 12.74% and a large Voc of 0.94 V, and the PSCs containing phthalimide-based polymer PhI-ffBT show a further increased PCE of 13.31% with a higher Jsc of 19.41 mA cm-2 and a larger fill factor of 0.76. The 13.31% PCE is the highest value except the widely studied BDT-based polymers and is also the highest among all benzothiadiazole-based polymers. The results demonstrate that phthalimides are excellent building blocks for enabling donor polymers with the state-of-the-art performance in nonfullerene PSCs and the BDT is not necessary for constructing such donor polymers.
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